A quantitative method for metamizol-Na in suppositories made with Witepsol H-15 as fatty matrix, using High Performance Thin Layer Chromatography (HPTLC) is proposed and validated. Rosemont procedure based on statistical analysis of accuracy, precision, linearity and proportionality through the analytical assay of six replicates and three concentration levels representing 90, 100 and 110% of declared concentration was used. Accordingly validation procedure, the method is convenient and trustful because the Confident Limit of mean includes 100% of recovery, precise (CV = 2.45), linear (RV = 7.77 < F = 8.66), and proportional since Confident interval of intercept includes zero. The HPTLC method, proposed for quantitative analysis of metamizol-Na in suppositories do not differ statistically from the Official Method described in the German Pharmacopeia